Just curious but too lazy to try it myself.
Caesar is very killable with a stealthy headshot of sneaked-in .44 revolver, and then you can run away from the camp using high speed and stealthboy too. What ending will it bring out?
Same with Benny, headshot and run for exit from casino. What will it affect?

Apart from faction hostility? The Legate will command Caesars Legion and Benny will... die, you'll also get some idle NPC pvssyr.

IIRC apart from a few small spats of dialogue and DJ banter on RNV, not much changes in the game.

Killing Benny or Caesar has relatively little impact on the gameworld whenever you do it, just the odd npc comment and radio report. Doing either earlier rather than later wouldn't have much if any impact on the ending I would've thought.

If you don't mind feeling cheap for taking advantage of game mechanics Benny is quite easy to take out on the casino floor with no repercussions at all. You can push Benny over to the nearby stairwell, shove him in to the corner with the potted plant, and as long as you dispatch him quickly no one will be the wiser. For some reason he won't move back to his spot no matter how far you push him and his guards don't follow - they'll actually just hang out there for the rest of the game.

It's impossible to kill Benny "early." The moment you see him again is when you're supposed to try killing him.

That's what my first character did... and succeeded! "Yeah, sure, right, I'll just head up stairs and wait for you..." *shoots Benny in the face*

Sure did piss off the guards though. And Boone died in the ensuing chaos. :sadvaultboy: